1. Field of the Invention
The present invention relates to rail car braking systems, and more particularly to a rail car brake monitoring apparatus for monitoring the status of a rail car brake system.
2. Description of the Prior Art
Conventional rail car brake systems include a plurality of brake shoes, a mechanical linkage assembly coupled with the brake shoes for pressing the brake shoes against the rail car's wheels when the linkage is shifted to a braking position, and a pneumatically-operated brake cylinder that, when actuated, shifts the mechanical linkage to its braking position. Rail car brake systems also include a manually-operated hand brake in each rail car that shifts its mechanical linkage to the braking position. The hand brakes are applied when the train is "parked" for preventing the rail cars from moving while not coupled with a locomotive for a time. The hand brakes are then manually released when the locomotive is once again coupled and the brake systems recharged so that the brake systems in the rail cars are once again controlled by their pneumatic brake cylinders.
Unfortunately, train operators often omit releasing the hand brakes in all of the rail cars before the train is moved. Thus, the brake shoes remain in contact with the rail car's wheels while the train is moving, causing rapid and premature wear of the brake shoes and wheels and sometimes even rail car derailment.
Rail car brakes also sometimes fail to release when their mechanical linkages get stuck or when their cylinders fail. These failures also result in brake shoe and wheel wear and possible derailment.
Another limitation of conventional rail car brake systems is that they do not include means for monitoring the wear on their brake shoes. Since the brake shoes often wear rapidly, operators must frequently visually inspect the brake shoes. Those skilled in the art will appreciate that such visual inspections are time consuming and imprecise. Complicating the problem, the brake shoes on different rail cars wear at different rates due to many factors including the amount of weight in the rail cars. Thus, operators cannot accurately predict when brake shoes will wear out and therefore must frequently inspect all the brake shoes on all of the rail cars regardless of the age of the brake shoes.